Gemini 3.5 Flash vs GLM-5.1
Benchmarks, API pricing and specs, head to head. Data updated 2026-06-10.
Google · May 2026
Google's I/O 2026 headliner: near-Pro intelligence at Flash speed, 78.8% on SWE-bench Verified with full multimodal input.
Z.ai (Zhipu) · Apr 2026
The April 2026 GLM refresh — the first open-weights model to take #1 on SWE-bench Pro, edging out Claude Opus 4.6.
The verdict
These two models don't yet share verified results on the benchmarks we track, so judge them on specs, pricing and intended use. GLM-5.1 is about 1.6x cheaper per blended million tokens (3:1 input:output mix). Gemini 3.5 Flash also takes 1M of context versus 200K for GLM-5.1. And GLM-5.1 is open-weights (MIT), so it can be self-hosted — a structural advantage if data control or vendor independence matters.
Specs & pricing
| Gemini 3.5 Flash | GLM-5.1 | |
|---|---|---|
| modhub Index | — | — |
| Input price / 1M | $1.5 | $1.4 |
| Output price / 1M | $9 | $4.4 |
| Context window | 1M | 200K |
| Max output | 66K | 128K |
| Open weights | no | yes (MIT) |
| Reasoning model | yes | yes |
| Multimodal input | text, image, audio, video | text |
| Knowledge cutoff | Feb 2026 | Feb 2026 |
| Released | May 2026 | Apr 2026 |
| Example monthly cost* | $28.50 | $20.60 |
* 10M input + 1.5M output tokens per month at list prices, no caching. Green = better value on that row.
Frequently asked questions
- Which is better, Gemini 3.5 Flash or GLM-5.1?
- These two models don't yet share verified results on the benchmarks we track, so judge them on specs, pricing and intended use. GLM-5.1 is about 1.6x cheaper per blended million tokens (3:1 input:output mix). Gemini 3.5 Flash also takes 1M of context versus 200K for GLM-5.1. And GLM-5.1 is open-weights (MIT), so it can be self-hosted — a structural advantage if data control or vendor independence matters.
- Which is cheaper, Gemini 3.5 Flash or GLM-5.1?
- Gemini 3.5 Flash costs $1.5/$9 per million input/output tokens, while GLM-5.1 costs $1.4/$4.4. For a typical workload of 10M input and 1.5M output tokens per month, that's $28.50 versus $20.60.
- Which model is better for coding, Gemini 3.5 Flash or GLM-5.1?
- We don't yet track SWE-bench Verified results for both models; check their individual pages for coding-related scores.